Segment Information Revenue by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2016	Oct. 25, 2015	Jul. 26, 2015	Apr. 26, 2015	Jan. 25, 2015	Oct. 26, 2014	Jul. 27, 2014	Apr. 27, 2014	Jan. 31, 2016	Jan. 25, 2015	Jan. 26, 2014
Revenue from External Customer [Line Items]
Net sales	$ 118,609	$ 115,810	$ 125,712	$ 130,088	$ 130,394	$ 148,890	$ 145,742	$ 132,859	$ 490,219	$ 557,885	$ 594,977
Signal Integrity and Timing Products [Member]
Revenue from External Customer [Line Items]
Net sales									221,185	219,024	254,556
Protection Products [Member]
Revenue from External Customer [Line Items]
Net sales									138,674	191,341	198,514
Wireless and Sensing Products [Member]
Revenue from External Customer [Line Items]
Net sales									70,712	80,632	65,947
Power Management and High Reliability Products [Member]
Revenue from External Customer [Line Items]
Net sales									54,999	64,402	58,295
Systems Innovation [Member]
Revenue from External Customer [Line Items]
Net sales									$ 4,649	$ 2,486	$ 17,665
Sales Revenue, Goods, Net [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									100.00%	100.00%	100.00%
Sales Revenue, Goods, Net [Member] | Signal Integrity and Timing Products [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									45.00%	39.00%	43.00%
Sales Revenue, Goods, Net [Member] | Protection Products [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									28.00%	34.00%	33.00%
Sales Revenue, Goods, Net [Member] | Wireless and Sensing Products [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									14.00%	14.00%	11.00%
Sales Revenue, Goods, Net [Member] | Power Management and High Reliability Products [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									11.00%	12.00%	10.00%
Sales Revenue, Goods, Net [Member] | Systems Innovation [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage									1.00%	0.00%	3.00%